In refilling the fuel tank of a motor vehicle with liquid fuel, usually gasoline, a fuel nozzle is inserted into the filler pipe leading to the fuel tank, and the liquid fuel is discharged through this nozzle and the filler pipe into the tank. The operator may hold the nozzle valve open manually, or the valve may be held open mechanically, but in either case, the nozzle usually incorporates an automatic shut-off device which effects closing of the nozzle when the fuel in the tank reaches a certain level.
Typically in such refueling operations, since the fuel is volatile, a portion will evaporate, and the resulting fumes can escape into the atmosphere through the space between the outer surface of the nozzle and the inner surface of the filler pipe, as well as through the filler pipe while its cap is removed but the nozzle is not in the pipe. Minimizing of the resultant pollution of the surrounding atmosphere, as well as of the potential of explosion, has been the subject of research and development for some years.
For example, Vest U.S. Pat. No. 3,903,942 proposed that the filler tube for a vehicle fuel tank be provided at its outer end with a tubular "adapter member" of elastomeric material, e.g. neoprene. This tubular member has a normally constricted inner end so that as the fuel nozzle is inserted from the outer end, the inner end of the adapter member will expand to engage the outer surface of the nozzle and at the same time to seal whatever space would otherwise exist between the nozzle and the filler pipe. As another example, Maeroff U.S. Pat. No. 4,323,166 discloses a seal of elastomeric material for a fuel tank which has a filler opening without a filler pipe. This seal comprises a tubular body having an axially outer portion which forms a seal with the nozzle, and a tubular extension which depends into the tank.
A practical difficulty which affects prior art seals of the type described above is that they are subject to damage by the forced entry of a fuel nozzle, particularly when they are relatively-stiff as a result of cold weather. The damage may occur in the form of undue elongation tending to pull the seal away from its mounting or tearing. Also, if the nozzle is not in the proper position with respect to the seal, the automatic shut-off valve in the nozzle may be prevented from properly sensing the liquid level in the tank and thereby be rendered inoperative.